The present invention relates to a new and improved construction of a pneumatic vehicle tire, especially a radial-ply truck tire.
In its more particular aspects, the present invention relates to a new and improved construction of a pneumatic vehicle tire, especially a radial-ply truck tire which comprises a tread and ribs extending in the circumferential direction of the tread and separated by zig-zag-shaped grooves from each other. The cross-section of the central grooves decreases in a direction towards the base of each such groove.
In most cases radial-ply truck tires are provided with a tread which is subdivided in transverse direction into a predetermined number of ribs by zig-zag-shaped grooves extending in circumferential direction of the tread. It is also standard practice to form the sidewalls of the grooves at some inclination so that the groove narrows in the direction towards the base of the groove. This measure has the purpose of favorably affecting the rejection of foreign bodies, particularly stones, during driving. In this respect it has been suggested, for example, in U.S. Pat. No. 2,604,920, to arrange each of the sidewalls of the groove at respective constant inclinations or angles with respect to a line extending perpendicular to the tread.
In a further construction of tire as known, for example, from Austrian Pat. No. 309,250, the sidewalls of the grooves, instead of having a constant inclination, have an inclination which varies in a helical manner in circumferential direction. Such structure of the profile favorably affects wear after longer driving periods or service times and along straight routes. However, the rejection of foreign bodies during driving is only slightly enhanced by this type of profile. For this purpose a greater flare or opening angle of the groove would be required, whereby, however, the useful or positive tread or driving surface is reduced. Furthermore, only moderate traction can be expected from this known tire structure as well as from other known tire designs due to the identical zig-zag run or extension and due to the substantially symmetrical design of the groove sidewalls.